Frozen Pests: Recent Cold Snap Good for Massachusetts Forests

Some insects are just like humans. When the temperatures drop, they can’t handle it. Take, for example, the hemlock wooly adelgiad which has been infecting and killing hemlock trees in Massachusetts since the 1980’s. Rick Harper is a forestry professor at UMass Amherst. He says, for this bug, if “we get temperatures down in the single digits, five degrees Farenheit or so, you can see some really significant knockback of the populations.”

But the cold alone won’t be enough to get rid of this invasive species. This is Ken Gooch, director of the state’s Forest Health Program. “7 to 8 years ago, we had a quite a good cold snap, and we actually saw the populations drop 80-90%,” says Gooch. “But the populations rebounded in 3 to 4 years. They were right back.”

Another reason you can’t count on the freeze to significantly improve the health of New England forests? The two other prominent invasive insects in Western Massachusetts, the Asian longhorned beetle and the emerald ash borer, are too well insulated to be affected by the cold.